The present invention is generally related to fuel-fired heating appliances, and more specifically to a controller for a fuel-fired heating appliance capable of communicating diagnostic information.
Many control systems for controlling the operation of fuel-fired heating appliances have the capability of reporting diagnostic information relating to various components in the appliance. Some of these controllers also include a fuse for providing over-current protection for the controller and other electrical components of the appliance system. While such controllers included a field-replaceable fuse to protect the controller from mis-wiring or overload, these controllers were subsequently disabled when the fuse was blown or opened. Consequently, the control was unable to report diagnostic information concerning the open fuse or other appliance errors to a service technician. Furthermore, the prior art devices could not store diagnostic information if power to the control was interrupted. Thus diagnostic information was not available, even upon restoration of power. In an example of a fuel-fired furnace having a safety switch that disconnects power to the control when the service panel is opened, the control would lose diagnostic information when a technician opened the service panel to better view the control's diagnostic display. For the technician attempting to service a disabled furnace in which dirt accumulation was inhibiting visible access of the diagnostic display, a solution to this problem would be very helpful.